In the medical world, certain events that happen in the care of a patient are called sentinel events. These are unexpected events that cause serious physical or psychological injury or harm to a patient. These are usually procedure-based events such as operating on the wrong extremity or inadvertently puncturing an organ when doing a procedure. One would imagine that the delineation between what is and what is not a sentinel event is pretty straightforward. Sometimes it is, sometimes it isn’t.

In the career of a neurosurgeon or orthopedic surgeon, there is a 20% chance of operating on the wrong side extremity, wrong finger, or wrong level of spine. How does this happen? Pretty easily.

The usual situations are that the surgeon has reviewed his schedule for the day and then at the last minute the order of patients has changed. In his mind, he remembers that he is doing 3 left knees then one right knee. However, with the last minute change the order changes and somehow he operates on the wrong side.

Another situation is that in the chart, it is documented incorrectly that the patient’s left side is the operative side. However, it is really his right side. Usually it happens because both extremities are injured or show pathology but only one of them is being operated on. The surgeon may look at the X-ray to clarify and decide that the other side is the operative side, when in fact the patient wanted the other side operated on.

When it comes to the spine, things can often get confused. The normal anatomy of a person’s spine has landmarks to represent various levels. When the patient has an anomalous anatomy, an extra vertebrae, or a missing level, the surgeon can get confused.

All of these could be considered sentinel events because they cause harm to the patient. Specifically, the normal side or level was operated on.

While these may be obvious, sometimes they are not. For example, if a patient needs something during the surgery but it is not explicitly written on the consent form, it is a sentinel event to perform that part of the procedure without consent.